Aspirin is a common drug for relieving minor aches, pains, and fevers. People also use it as an anti-inflammatory or blood thinner.

People can buy aspirin over the counter without a prescription. Everyday uses include relieving headache, reducing swelling, and reducing a fever.

Taken daily, aspirin can help to lower the risk of cardiovascular events, such as a heart attack or stroke, in people with a high risk. Doctors may administer aspirin immediately after a heart attack to prevent further clots and heart tissue death.

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Aspirin is a nonsteroidal anti-inflammatory drug (NSAID). It was the first of this class of drug to be discovered.

Aspirin contains salicylate, a compound found in plants such as the willow tree and myrtle. Its use was first recorded around 4,000 years ago.

Hippocrates used willow bark for relieving pain and fevers, and some people still use willow bark as a natural remedy for headaches and minor pain.

NSAIDs are a class of drug with the following effects:

  • relieving pain
  • reducing fever
  • lowering inflammation, in higher doses

These drugs are not steroids. Steroids often have similar benefits to NSAIDs, but they are not appropriate for everyone and can have unwanted side effects.

As analgesics, NSAIDs tend to be non-narcotic. This means that they do not cause insensibility or a stupor.

Aspirin is a trademark owned by the German pharmaceutical company Bayer. The generic term for aspirin is acetylsalicylic acid.

Aspirin has many uses, including relieving pain and swelling, managing various conditions, and reducing the risk of cardiovascular events in people with a high risk.

Below, we describe these uses in more details.

Pain and swelling

Aspirin can relieve mild to moderate pain, swelling, or both associated with many health issues, such as:

For severe pain, a doctor may recommend using aspirin alongside another drug, such as an opioid pain reliever or another NSAID.

Preventing cardiovascular events

The daily use of low-dose aspirin can lower the risk of cardiovascular events in some people — it is not safe for everyone. The Food and Drug Administration (FDA) recommend only using aspirin in this way under the supervision of a doctor.

In people with a high risk of cardiovascular events, low-dose aspirin can reduce the risk by preventing blood clots from forming. Health experts may recommend low-dose aspirin as secondary prevention in individuals that have already experienced:

  • a heart attack
  • stroke
  • stent
  • bypass surgery
  • atherosclerotic cardiovascular disease (ASCVD)

Previous guidelines advised that low-dose aspirin was recommended for individuals with risk factors, such as high cholesterol, high blood pressure, smoking, or diabetes. However, unless a person’s overall cardiovascular risk is very high, the potential side effects, such as bleeding, outweigh the possible benefits.

The U.S. Preventive Services Task Force (USPSTF) guidelines advise that a doctor will consider a person’s overall 10‑year cardiovascular risk and the individual bleeding risk before recommending aspirin.

Treating coronary events

Doctors may administer aspirin immediately after a heart attack, stroke, or another cardiovascular event to prevent further clot formation and cardiac tissue death.

Aspirin can also be part of a treatment plan for people who have recently had:

Other uses

Aspirin can also help treat pain and swelling associated with the following chronic health conditions:

Doctors may recommend low-dose aspirin to people with established cardiovascular disease for secondary prevention. They may also advise low-dose aspirin for people with a high 10-year ASCVD risk and low bleeding risk.

Doctors do not usually recommend aspirin for people under 18.

This is because it can increase the risk of a serious condition called Reye’s syndrome, which can appear after a viral infection such as a cold, the flu, or chickenpox. Reye’s syndrome can lead to permanent brain injury or death.

However, a clinician may prescribe aspirin to a child under supervision if they have Kawasaki disease or to prevent blood clots from forming after heart surgery.

For children, doctors usually recommend acetaminophen or ibuprofen, in appropriate doses, instead of aspirin.

People with the following conditions should be cautious about taking aspirin, and should only do so if a doctor recommends it:

Under a doctor’s supervision, people who are pregnant may take low-dose aspirin. Doctors usually do not recommend high-dose aspirin during pregnancy due to potential risks to the fetus.

Anyone with a known allergy to aspirin or any other NSAID, such as ibuprofen, should avoid these drugs.

Doctors do not administer aspirin during a stroke because not all strokes are caused by blood clots. In some cases, aspirin could make a stroke worse.

Also, anyone who drinks alcohol regularly or is undergoing dental or surgical treatment, however small, should ask a doctor before taking aspirin.

An interaction may involve one medication making another less effective or the combination being dangerous.

Aspirin can interact with many drugs. Some of these include:

  • Anti-inflammatory painkillers: Examples include such as diclofenac, ibuprofen, and naproxen. Combined with aspirin, these types of drugs can increase the risk of stomach bleeding.
  • Selective serotonin reuptake inhibitors and other antidepressants: Examples include citalopram, fluoxetine, paroxetine, venlafaxine, and sertraline. In combination with aspirin, any of these can increase the risk of bleeding.
  • Warfarin: In combination with this blood thinner, aspirin can reduce the drug’s anticoagulant effects and increase the risk of bleeding. There are situations, however, when this combination may be beneficial.
  • Methotrexate: In combination with this drug, used in the treatment of cancer and some autoimmune diseases, aspirin can make the drug harder to eliminate, potentially resulting in levels of methotrexate that are toxic.

The most common side effects of aspirin include:

The following adverse effects are less common:

  • worsening asthma symptoms
  • vomiting
  • stomach inflammation
  • stomach bleeding

Aspirin can also have very serious side effects, such as bleeding in the brain or stomach or kidney failure. A rare side effect of daily low-dose aspirin is hemorrhagic stroke.

Aspirin can help prevent and treat a range of health issues, but people under 18 should not take it without medical guidance.

Aspirin is available over the counter or by prescription. Always follow the instructions on the label or a doctor’s guidance. This is especially crucial for people who may be more likely to experience adverse effects.

Aspirin is not safe for everyone, especially in a daily dosage. Other options for mild pain relief include other NSAIDs, such as ibuprofen, and acetaminophen.